'tachypneic' originates from modern medical formation combining Greek elements: 'tachy-' (from Greek 'tachys' meaning 'swift') and 'pnea' (from Greek 'pnoē' meaning 'breath'), formed via Neo-Latin/medical usage into the adjective suffix '-ic'.

'tachypneic' developed from the noun 'tachypnea' (a late 19th/early 20th century medical coinage) by adding the adjectival suffix '-ic' to create 'tachypneic'; the British spelling variant 'tachypnoeic' reflects the Greek 'pnoē' element.

Initially built to denote the condition 'rapid breathing' as the noun 'tachypnea'; the adjectival form 'tachypneic' later came to be used to describe patients or signs exhibiting that rapid breathing.